Photoacoustic Tomography for Finger Joint Imaging: Tackling Artefacts

Reumatoid Arthritis (RA) is an auto-immune disease which expresses itself as a chronic joint inﬂammation. Photoacoustic tomography is an imaging modality which is able to image small blood vessels in the ﬁnger with a high signal to noise ratio and can potentially be used to diagnose RA in an early stage.
Drawing conclusions from the photoacoustic images has proven to be challenging. Many artefacts are present on the images from which the origin and behavior are unknown. The artefacts are investigated by theoretical explanation and simulating scenarios in which the artefacts occur. It was found that the major artefacts in the photoacoustic images arise due to acoustic pressures waves from blood vessels scattering and reﬂecting on the bone surface. It was also found that when the location of the blood vessels and the shape and size of the bone is known, the artefacts in the photoacoustic image can be predicted and replicated in simulations.
Additionally, a 3D visualization tool is presented which is able to visualize the blood vessels of an imaged patient ﬁnger. From the results of this tool it is possible to observe diﬀerences between the vascularity and density of the blood vessels in a healthy and an inﬂamed ﬁnger.